In a conventional linear drive compressor, a piston is adapted to be moved in a reciprocating movement in a cylindrical portion of a housing. The piston is supported by flexure bearings for avoiding sliding engagement of the piston with the cylindrical portion of the housing. The reason for this structure is that the sliding engagement causes contamination of the coolant gas and deterioration of the seal ring that is mounted on the piston, problems that inevitably lower the performance of the compressor.
Japanese Patent Laid-Open Publication No. Hei 5-288419, published without examination on Nov. 2, 1993, discloses a flexure bearing for use in a linear drive compressor. This flexure bearing, which is illustrated in FIG. 4 of the present application, consists of a flat disc which is formed with a plurality of spirally arranged slits 19d. The outer periphery 19a1 of the flat disc 19a of the flexure bearing 19 is supported within the housing and the inner periphery 19a2 of the flat disc 19a of the flexure bearing 19 is connected to the piston. With the piston supported in this manner, the flexure bearing 19 is very rigid in the radial direction and very flexible in the axial direction. Thus, the flexure bearing 19 is able to provide a non-contacting and no-wear relationship between the piston and the cylindrical portion of the housing while the piston is moving in a reciprocating manner.
However, when the stroke of the piston is increased for achieving greater power or performance of the linear drive compressor, and/or when the diameter of the flexure bearing is reduced for obtaining a lighter linear drive compressor, stress concentrations appear at opposite extreme ends of each slit and this can cause cracks to occur or tearing-off at the ends. It has been found that these problems cannot be addressed by a mere modification of the flexure bearing.
A need thus exists for a flexure bearing which is not susceptible of the same disadvantages and drawbacks discussed above.
It would thus be desirable to provide a flexure bearing which is not susceptible to crack formation or tearing-off at the extreme ends of the slits formed in the flat disc of the bearing.